Here's a breakdown:

* Lithosphere: This is the rigid, outermost layer of Earth, composed of the crust and the uppermost part of the mantle. It's broken into tectonic plates.

* Asthenosphere: This is a semi-solid, partially molten layer of the upper mantle, located beneath the lithosphere. The asthenosphere is less rigid than the lithosphere and allows the tectonic plates to move on top of it.

Think of it like this: imagine the Earth's crust and uppermost mantle as a giant puzzle made of thick, rigid pieces (the tectonic plates). These pieces float on a layer of slightly gooey, flowing material (the asthenosphere).